Lever

Q. A square card board is suspended from by passing a pin through a narrow hole at its one corner.Draw a diagram to show its rest position.In the diagram make the point of suspension by the letter S and the centre of gravity by the letter G.

Q. A uniform flat circular rim is balanced on a sharp vertical nail by supporting it at a point $A$, as shown in the below figure. Mark the position of the centre of gravity of the rim in the diagram by the letter G.

Q.

What is a lever? State its principle.

Q.

A 4 m long rod of negligible weight is supported at a point 125 cm from its one end and a load of 18 kgf is suspended at a point 60 cm from the support on the shorter arm.

(a) if a weight W is placed at a distance of 250 cm from the support on the longer arm, find W.

(b) If a weight 5 kgf is kept to balance the rod, find the position.

(c) To which class of lever does it belong ?

Q.

What is the principle of lever?

Q.

Draw diagrams to illustrate the positions of fulcrum, load and effort, in each of the following :

(a) A seesaw (b) A common balance

(c) A nut cracker (d) Forceps.

Q. The fixed point about which a lever turns is called:

1. Effort
2. Fulcrum
3. Pulley
4. Load

Q. What is the position of the centre of gravity of a rectangular lamina?

Q. If the effort arm is longer than the load arm, the lever is a .

1. force multiplier
2. speed multiplier
3. time multiplier

Q.

In fig below shows the use of a lever.

(a) State the principle of moments as applied to the above lever.

(b) To which class of lever does it belong? Give an example of this class of lever.

(c) If FA = 10 cm , AB= 490 cm, calculate : (i) the mechanical advantage, and (ii) the minimum effort required to lift the load (= 50 N).

Q.

What is a device which is used to lift a car?

Q. State whether the following statement is true or false:
The centre of gravity of a freely suspended body always lies vertically below the point of suspension.

Q. Figure shows three pieces of card board of uniform thickness cut into three different shapes.On each diagram draw two lines to indicate the position of the centre of gravity $G$.

Q.

Both a pair of scissors and a pair of pliers belong to the same class of levers. Name the class of lever. Which one has the mechanical advantage less than 1 ?

1. They belong to class I lever, pair of pliers has a mechanical advantage < 1

2. They belong to class II lever, pair of pliers has a mechanical advantage < 1

3. They belong to class III lever, pair of pliers has a mechanical advantage < 1

4. They belong to class I lever, scissors have a mechanical advantage < 1

Q. A lever works on the principle of:

1. Moments
2. Gravitation
3. Momentum
4. Friction

Q.

A cook uses a fire tong of length 28 cm to lift a piece of burning coal of mass 250 g. If he applies his effort at a distance of 7 cm from the fulcrum, then the effort required in SI units will be? Take g= 10 m s^-2.

Thala for a reason

Dhoni

Mahendra Singh dhoni

MSD

Q. If the load is closer to the fulcrum, it will take to lift the load.

1. more effort
2. less effort
3. no effort

Q.

What is the fulcrum of a lever?

Q.

6.4 kJ of energy causes a displacement of 64 m in a body in the direction of force in 2.5 seconds. Calculate the Force applied

1. 100 N

2. 6.4 N

3. 64 N

4. 50 N

Q.

A man uses a crowbar of length 2.5 m to raise a load of 75 kgf by putting a sharp edge below the bar at a distance 1 m from his hand. State the kind of lever used and calculate the effort needed.

1. Class II lever, 35 kgf

2. Class I lever, 50 kgf

3. Class III lever, 37.5 kgf

4. Class I lever, 35 kgf

Q.

Calculate the amount of force P which will just lift the total weight of 200 N acting on the wheelbarrow as shown in figure.

1. 87.89 N

2. 89.56 N

3. 91.90 N

4. 90.91 N

Q.

A fire tong used to lift the coal from fire is what type of machine?

1. Inclined plane

2. Lever

3. Wedge

4. Pulley

Q.

One end of a spring is kept fixed while the other end is stretched by a force as shown in the diagram.

Name one instrument which works on the above principle.

1. Beam balance

2. Spring balance

3. Cantilever

4. Oscilloscope

Q. is an example of class III lever.

1. Broom
2. Scissors
3. See-saw

Q.

The mechanical advantage of a machine is $5$. How much load it can exert for the effort of $2Kgf$.

Q.

A movable pulley system consists of three movable pulleys and one fixed pulley. Calculate the distance moved by the load when effort moves by 80cm

1. 40 cm

2. 640 cm

3. 240 cm

4. 10 cm

5. 40 cm

Q.

State the lever that always has a mechanical advantage less than 1.

Q.

A $8m57cm$ pole was put in a pond to measure its depth.

If $4m66cm$ of pole remained outside water, then the depth of the pond is?

Q. Lever of second order has _________ at centre.

1. fulcrum

2. load

3. effort

4. load arm

Q.

A single fixed pulley does not change the direction of applied effort.

1. True
2. False